MLX90320_12 Datasheet, PDF (20/33 Pages) Melexis Microelectronic Systems – Automotive sensor interface

6.5.3 Communication Request
MLX90320
Automotive sensor interface
1) Pattern to enter the communication mode
COM pin :
analog signal
Short-circuit to
VDD
Short-circuit to
VDD
Digital Signal
Short-circuit to the GROUND
Short-circuit to the GROUND
1.5ms +-
30%
1.5ms +-
30%
<1ms
1.5ms +-
30%
1.5ms +-
30%
< 90ms
2) First case : the analog level is quite high :
COM pin :
IRQ :
Has to stay LOW
at min 1.0 ms
at max 2.0 ms
A LOW level should
be seen within 3 ms
3) Second case : the analog level is quite low :
Has to stay
LOW at
min 1.0 ms
at max 2.0
ms
A HIGH level should be
detected within 3 ms
Waiting for the first bit = 90 ms
COM pin :
IRQ :
Has to stay HIGH
at min 1.0 ms
at max 2.0 ms
A HIGH level should be
seen within 3 ms
Has to stay
HIGH at
min 1.0ms
at max
2.0ms
A HIGH level should be
detected within 3 ms
Waiting for the first bit = 90 ms
The default mode is the receive mode. The user has to send a valid command to the interface chip.
6.5.4 Bit format
The bit is coded into a pulse width modulated format (PWM).
PWM format has no need for message frame synchronization. This has the advantage that the receive speed can
differ from the transmit speed. There is no configuration needed, the receiver can work with various bit rates.
1
5 Volts
0 Volt
0
5 Volts
0 Volt
A valid bit always starts with a falling edge. This means that after making a communication request by shorting to
ground, the user must reset the output line to high status.
3901090320
Page 20 of 33
Data Sheet